Hand-held tiller 

Mulch-till

Double-digging method 

Impact of tillage on soil's microbial community 

Several studies have assessed the impact of different farming practices on soil microbial communities.

Tillage affects the microbial community of soils, and thus, its health and fertility.  

If you're trying to get your garden ready for planting, consider the double-digging method.

Tilling Your Backyard